WASHINGTON: The number of US teens owning smartphones has risen sharply in the last year, and these devices are rapidly becoming their preferred method of going online, the Pew Research Center has found.

The think tank surveyed 802 teens and their parents in the second half of 2012 for a report entitled Teens and Technology and found that 78% of US teens aged 12-17 had a cellphone and almost half of those (47%) owned a smartphone.

Across the teenage group as a whole, that meant 37% of all teenagers owned a smartphone, a sharp rise on the previous year when just 23% of teens owned one.

Around three quarters (74%) accessed the internet on cell phones, tablets, and other mobile devices at least occasionally.

Overall, one in four teens were "cell-mostly" internet users, a significantly higher proportion than adults, among whom just 15% could be thus described. And among teen smartphone owners, half were cell-mostly.

"The nature of teens' internet use has transformed dramatically," said Mary Madden, senior researcher for the Pew Research Centre's Internet Project and co-author of the report.

It has moved, she explained, "from stationary connections tied to shared desktops in the home to always-on connections that move with them throughout the day."

"In many ways, teens represent the leading edge of mobile connectivity," she added, "and the patterns of their technology use often signal future changes in the adult population."

It is a trend that brands will take note of as they increasingly favour the mobile as a marketing channel to reach young consumers.

The study also found that older girls, aged 14 to 17, were more likely to go online using their cellphone, with 34% of this group doing so against 24% of similarly aged boys.

Income levels appeared no barrier to teen smartphone ownership, as the report revealed that this was not tied to their parents' income levels.  Teens in the lowest-earning households were just as likely as those in the highest to own smartphones.

Data sourced from Internet Advertising Bureau UK, Pew; additional content by Warc staff